Easy-open containers have been used for a variety of products, including powdered materials, such as food products, cleaning products, etc. Easy-open containers are often constructed of a composite cylindrical body portion having end closures for closing and sealing the container. In some examples, the top end closure comprises an end ring, fixed to the container body, and an inside circular peripheral rim in the form of an inwardly directed flange, which may include a downwardly curved bead. The inner rim defines a central opening of desired size for access through the rim and into the interior of the container. A removable membrane patch covers the central opening and may be attached to the inwardly extending flange. To open the container, the membrane patch is detached from the container, providing access to the product therein.
Easy-open containers often include overcaps, fitting over the container top end portion and top end closure. The overcap serves many functions including, but not limited to, protecting the top of the container from damage before and after removal of the membrane, keeping unwanted items from getting into the container, keeping the product within the container from spilling out, helping to improve stacking of the container, and increasing the life of the product after opening.
Some products, such as roasted or ground coffee, tend to give off gases for a period of time after their preparation. Ground coffee releases carbon dioxide and other gaseous substances for days or weeks after the grinding process. Because of this gas release, sometimes called “off-gassing”, it is customary to store the coffee in packaging that can expand or that has a release vent on the package. Flexible packaging having a one-way gas release valve thereon is shown in, for example, Goglio U.S. Pat. No. 3,595,467, Donke U.S. Pat. No. 5,326,176 and Walters U.S. Pat. No. 5,992,635. Semi-rigid containers with vent valves are shown in, for example, Gunter et al U.S. Pat. No. 7,294,354 and Thomas et al U.S. Pat. No. 7,074,443.
When a flexible seal is provided on a more rigid container having materials subject to off-gassing, an amount of flexing occurs on the seal, prior to the provided valve venting the built up pressure within the container. In the Thomas et al patent mentioned above, the valve is provided on the flexible sealing material and a stand-off is provided on the underside of the overcap so that the valve may function properly. Another method of venting may be accomplished by positioning the valve on the membrane in a position that will prevent the valve from engaging the overcap during expansion of the flexible lid. In the Gunter et al patent mentioned above, the valve is provided on the outer surface of the container.
Another feature of overcaps for containers that is sometimes useful is a venting of pressure from within the container around the seal formed between the overcap and the rim or chime of the container. Various forms for causing this type of venting are shown in, for example, Clougherty U.S. Pat. No. 7,337,916, Holder et al U.S. Pat. No. 3,381,872 and Beall, Jr. U.S. Pat. No. 3,043,463.